Numatics Breakdown — Instrumentation Field Manual

Numatics Valve Components

Coil

Electromagnet (24VDC typical)

Creates magnetic field when powered — pulls plunger

Plunger

Metal armature pulled by magnet

Moves when coil energizes — drives the spool

Spool

Internal valve element

Shifts air paths when plunger moves

Spring

Return mechanism

Pushes spool back when de-energized — fail-safe

Ports (3-way)

P = Pressure (supply in)

A = Actuator (output)

R = Return (exhaust out)

Where You'll Find These — Process Plant

BAG CLAMPS S1–S8

Opens/closes bag sealing on packer

FEED GATE VALVES

Controls product flow to packer

BULK/DRIBBLE SWITCH

Fast fill then slow top-off

TUBE CLEANOUT

Air blast to clear fill lines

Live Solenoid Operation

DE-ENERGIZED STATE

Troubleshooting Game

Pick a failure mode, run tests, then diagnose it.

Electrical

Voltage (standard)24VDC

Also available120VAC, 12VDC

Coil resistance50–150Ω typical

Current draw0.2–0.5A @ 24VDC

Pneumatic

Supply pressure80–120 PSI

Min operating20 PSI

Max pressure150 PSI

Response time10–50 ms

Testing Values

Good coil50–150Ω

Open coil∞ (OL)

Shorted coil<10Ω

Voltage at coilMatch nameplate

Normal Operation

✓ Clean sharp click sound when switching
✓ Coil slightly warm — not hot
✓ Air switches immediately on command
✓ No continuous air leaks
✓ 120VAC at coil terminals (L1)

Bad Signs

✗ Silent — no click when energized
✗ Coil very hot to touch
✗ Buzzing or humming
✗ Air leaking continuously from exhaust
✗ 0VDC at coil terminals
✗ Clicks but air doesn't switch

// Field Tips — Process Plant

💡 BAG CLAMPS (S1–S8)

If clamp won't close: Check solenoid first before blaming the actuator. LED on coil = coil good.

💡 STICKY VALVES

Product buildup on plunger — clean or replace valve body. Coil may be fine.

💡 MANUAL OVERRIDE

Red/yellow button on top — push to test mechanical function without energizing coil.

💡 COIL REPLACEMENT

Usually just unscrew. Keep same voltage rating — wrong voltage = instant failure.